Chain saw



FIG. 1 is a perspective view of a chain saw showing my new design;

FIG. 2 is a right side elevational view thereof;

FIG. 3 is a left side elevational view thereof;

FIG. 4 is a front elevational view thereof;

FIG. 5 is a rear elevational view thereof;

FIG. 6 is a top plan view thereof; and

FIG. 7 is a bottom plan view thereof.

The broken line showing of the blade is for illustrative purposes only and forms no part of the claimed design. 

The ornamental design for a chain saw, as shown and described. 